Re: [PATCH for mm] Remove iBCS support

Andi Kleen
2008-01-20T05:15:06Z

On Sun, Jan 20, 2008 at 03:16:25PM +1030, David Newall wrote:
> Andi Kleen wrote:
> > On Sun, Jan 20, 2008 at 12:57:29PM +1030, David Newall wrote:
> >
> >> compatibility. This is a sleeping giant for Linux. There are plenty of
> >>
> >
> > Interesting choice of words.
> >
> KFC and Dominoes use SCO for their cash registers, to pick just two
> enormous future opportunities.

I suppose if they update their cash registers they will just go
with fully Linux binaries.

> > But it does not make sense for all Linux kernels to always check for iBCS executables
> > when they don't have to code to run them anyways.
> >
>
> I don't suppose you're suggesting this will make a big difference. Even
> if every exec did nothing but immediately exit, it still wouldn't make
> much difference.

It's not a big difference, but why do unnecessary work on all
Linux kernels? There are a lot of Linux machines out there and
if all of them only do a little unnecessary work each fork()
over a year it adds up to really a lot of wasted cycles.

Especially since the few people who might really
need it can easily readd it.

> Likewise, I take your point about proper iBCS support (and I suppose
> it's really iBCS2 that we're talking about.) My concern is that
> removing this now gains almost nothing, 2 strcmp per exec is as close to
> nothing as anything, but it sends a message with which I disagree. The
> message should be that Linux is good for, well the same things FreeBSD
> is, and includes running Solaris and SCO binaries. This is a major

But Linux is not good for this currently, at least not unless you
add a significant patch (which I'm not sure does even exist
for modern 2.6; iBCS was mainly deployed on 2.4 kernels). And when you
add that patch you can easily readd the strcmps too.

> simplification of the story, I know, but still hits the plot highlights.

You're worried about this patch generating headlines?

-Andi